Industry and public health advocates are unhappy with EPA's Dec. 20, 2005, proposal to tighten national standards for fine particles that pollute the air.

Industry groups, including the American Chemistry Council (ACC), say more research is needed before EPA strengthens its 1997 standards for fine particulate matter in air. Health groups such as the American Lung Association, as well as environmental activists and some state regulators, say the proposal does not go far enough to protect the public from the heart and lung ailments linked to breathing in particulate matter.

Fine particulate matter, produced by combustion in power plants and vehicles, is composed of solid and liquid aerosols sized 2.5 µm and smaller in diameter.

EPA is proposing to lower the daily average for the allowable amount of particulate matter in air from the current 65 µg/m3 to 35 µg/m3. EPA would retain the current annual average of 15 µg/m3, although the agency's Clean Air Scientific Advisory Committee recommended this benchmark be lowered to between 13 and 14 µg/m3.

T. Ted Cromwell, ACC senior director of regulatory and technical affairs, says scientists have yet to determine what chemical constituents of fine particles cause health problems. ACC believes the agency should retain its current standards until more data are available, he tells C&EN.

EPA's proposal could affect chemical manufacturing facilities in urban areas that are at or above the current standard for fine particulates, Cromwell adds. If the agency finalizes the proposed daily average standard of 35 µg/m3, plants in these areas, which already face stringent air pollution controls, may face tighter emissions requirements as localities struggle to meet the new benchmark, he explains.

In contrast, John L. Kirkwood, president of the American Lung Association, says the EPA proposal "falls far short of what is necessary to protect public health" as required by the Clean Air Act. More than 2,000 studies conducted since the 1997 standards were put in place show that, to protect people's health, the particulate-matter benchmarks need to be tougher than what EPA proposed, he says.

Some state regulators are also unhappy with the proposal.

"Given the wealth of supportive scientific evidence available upon which to base this decision, we expected EPA to propose more stringent standards," says Arthur Marin, executive director of NESCAUM, a regional association of air pollution agencies in eight northeastern states.

Meanwhile, EPA is also proposing to lower the current daily standard for coarser air particulates, which are sized between 2.5 µm and 10 µm in diameter, from 150 µg/m3 to 70 µg/m3. Unlike the current benchmark for coarse particulates, the proposal would not apply to windblown dust or soils.

EPA faces a court-imposed deadline of Sept. 27 to finalize its standards for fine and coarse particulate matter.